1. Field of the Invention
This invention relates to the improvements of a tomograph for photographing the entire jaws which is designed to obtain an X-ray photograph of the curved plane section of an object by transmitting the driving output of a driving motor for driving a rotary arm to a motor for feeding a film after having converted the output into an electric output by an eccentric cam means.
2. Prior Art
Concerning a method and an apparatus for obtaining an X-ray photograph of a curved plane section of the object by changing transfer factor of the rotating output of a rotary arm driving motor by an eccentric cam means (adapted to be rotated in accordance with rotation of the rotary arm) to control the film feed speed of a film feed device, the present applicant has already filed the following applications for above invention not only in Japan but also in the United States of America, Germany, Italy, and Finland respectively under U.S. Ser. No. 188,884, U.S. Ser. No. 131,689 and U.S. Ser. No. 131,709; German Patent Application No. P3010798.3, P3010799.4 and P3035436.0; Italian Patent Application No. 48220 A/80 and No. 48221 A/80; and Finnish Patent Application No. 802928.
The above-identified invention were designed to control a film feed speed by changing divided voltage output of potentiometer by an eccentric cam means which rotates in accordance with rotation of a rotary arm and leading the changed voltage to V/F converter circuit to thereby drive a pulse motor, and the curved plane section orbit of an object to be photographed was primarily specified by the configuration of the cam means. Accordingly, when the configuration of the object to be photographed, for example, the configuration of the dental arch was substantially the same, it was possible to continuously photograph a plurality of objects having no blurred points thereon, but when the objects are different in their configurations, it was impossible, in principle, to obtain a sharp picture of an object unless the object (patient) changed its position to be set or the cam used was replaced by one different in configuration.